Studies on the structure of macromolecules in cancer cells are essential for defining the biochemical lesion(s) distinguishing cancer cells from normal cells. This research proposal concerns 3 related topics: 1) A methodological investigation of postlabeling procedures for the sequence analysis of non-radioactive RNA; 2) sequence analysis of specific tRNAs; 3) Studies on the effects of antineoplastic drugs (e.g., 5-azacytidine, 5-fluorocytidine) on tRNA and DNA as well as tRNA methyltransferases and DNA methyltransferases. COMMENTS: Methods to be developed for the structural analysis of minute amounts of non-radioactive RNA will entail 3H-labeling and 32P-labeling, enzymatic and chemical digestions, chromatographic and electrophoretic separations. We wish to determine sequences of tRNAs that are rich in 5-methylcytidine because 5-azacytidine and 5-fluorocytidine were found in our laboratory to inhibit specifically the formation of this compound in nucleic acids. Preparation of nucleic acids deficient in a single constituent may enable one to define the biological role(s) of this constituent. In vivo studies are planned to investigate the effects of 5-azacytidine and 5-fluorocytidine on tRNA and DNA. In vitro studies will be aimed at elucidating the mechanisms of inhibition of RNA and DNA methylation by the nucleoside analogs. The sequences of tRNAs from tumors will be compared with their normal counterparts to define tumor-specific tRNA alterations.